The Studies of Pediatric Liver Transplantation (SPLIT) Registry, founded in 1995, is designed to characterize and follow trends and indications for transplant, transplantation techniques, and outcomes such as patient and graft survival, rejection incidence, growth parameters, immunosuppressive therapy and complications. Registry membership includes a central statistical and data Coordinating Center located at The EMMES Corporation in Rockville, Maryland, and 39 Transplant Centers from the US and Canada. Data is submitted over a secure password protected Internet data entry system. The activities of the registry are governed by a Scientific Advisory Board. This application seeks to secure 5-year funding in order to assess factors predicting both short and long-term (5 years or more) outcomes overall and within primary disease subgroups (biliary atresia, metabolic disease, tumor, autoimmune hepatitis, etc.). This funding will permit SPLIT to continue registration and close follow-up of patients. Registration of children in the database as of the 2002 Annual Report is 1,721 listed children with 1,187 receiving a transplant. Five-year follow-up is available for 64 children from 11 centers. If this grant were funded, by the end of the grant period it is estimated that 5-year data would be available from over 900 children from 36 centers. This would be the largest cohort of pediatric liver recipients with long term followup ever studied in the depth. This application focuses on two specific aims. The first is to develop and test models which predict short and long-term patient and graft survival and graft function of children after liver transplantation, as well as from the time of listing. Baseline factors including status at transplantation, operative factors and post-transplant complications will be evaluated and are expected to vary based on primary disease diagnosis. The second aim is to study long term consequences of liver transplantation and immunosuppression in children including: renal function, post transplant lymphoproliferative disease (PTLD), cardiovascular risk factors and growth failure. SPLIT's unique sample will allow determination of the prevalence of morbidities associated with long term immunosuppression and identification of the predictors of those morbidities. SPLIT provides an established organizational framework with a track record of success. No other research database exists that can address these questions that have been mandated by the Children's Health Care Act of 2000 (HR4365), and recognized by the Department of Health and Human Services and the Institute of Medicine (Federal Register 98-8191 ,IOM report, 1999) as priority research areas